Interplanetary Cycler
Tech level: 12

Most of this article is paraphrased from the Beyond 2000 article, "Flying Visit," author unknown. The link is given at the bottom of this page.

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"A cycler spacecraft is basically a space station in a complex interplanetary solar orbit. As the craft travels close to a planet, its flight path is bent, causing it to whip around the planet while boosting its speed. The path is commonly called a slingshot trajectory, which enables a spacecraft to achieve the proper speed and direction.

‘The cycler essentially is in orbit around the sun and makes regular flybys of Earth and Mars,’ explains team member James Longuski, a professor of aeronautics and astronautics at Purdue studying the possibility of an Earth-Mars cycler. ‘Once you put your vehicle into a cycler orbit, it continues on its own momentum, going back and forth between Earth and Mars. You may need to carry some propellant for an occasional boost, but it's pretty much a free trip after that.’

In practice a cycler might fly past the Earth at about 21,000 kilometers per hour. Transfer spacecraft carrying people and supplies would have to rendezvous with the speeding hotel.

‘This is sort of like a bus that doesn't stop,’ Longuski said. ‘When it comes by, you have to run alongside of it and grab on.’ The outbound trip to Mars would take six to eight months.

‘Then, when you get to Mars, you get in the taxi and de-orbit down to the planet,’ said Longuski, who is working with Purdue graduate students to design the trips from Earth to Mars and back.

‘These cyclers would be like space hotels,’ Longuski said. ‘They would provide the usual creature comforts.’

The spacecraft would rotate slowly to create artificial gravity and prevent the debilitating effects of weightlessness on its passengers. It would also be roomy enough to make the trip tolerable. The earliest versions of the space hotels might accommodate up to 50 passengers

The team say the machine will become a permanent, man-made inner solar system companion of Earth and Mars, tapping the free and inexhaustible 'fuel supply' of gravitational forces to maintain orbit. Like an ocean liner on a regular trade route, a cycler will glide perpetually along its beautifully predictable orbit.

However, it is difficult to precisely design cycler trajectories because of the complex orbital relationship between Earth and Mars as the planets travel around the sun. While the Earth orbits the sun in a nearly circular route, Mars' orbit is oblong, or elliptical. That means the distance between Mars and the Earth varies dramatically depending on Mars' orbital position around the sun, complicating the design of spacecraft trajectories between the two planets."

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Once the system is established and proven viable, multiple cyclers will probably be employed along the same route, staggered a few months or weeks apart. As this leads to much more frequent exchanges of goods and assets, this system would make interplanetary trade and multiple planet economies viable beyond the novelty stage. It would also enable a full-scale colonization and exploitation of major solar system bodies to become a reality.

Though an Earth-Mars cycler is the most talked about route, cyclers can be established between any two planetary bodies. As complex orbital mechanics become better understood, it may even be possible to create three or more body cycler routes.


Articles on Interplanetary Cyclers:

Article added 2005